It looks like Shadow has an early nadir, somewhere between +4 and +6. Can't really tell what time, because you only have a couple of tests at +5.
I think you need to increase to 3U.
Please post over in Lantus TR ISG for more advice from the folks over there. There aren't a lot of people that come over to the Feline Health forum to give dose advice.
In your post, ask for dose advice in your subject line.